Implantation of ions in a surface is a known process. It enables the properties of a surface to be improved by imparting to it characteristics derived from the implanted material. Thus, corrosion resistance and bearing properties, for example, can be improved. Because the improvement is imparted only to the surface, the penetration need not be especially deep for good results to be attained. Only very small quantities of implanted materials need be used, and for this reason materials having optimum properties can be utilized, even though their cost is so high that they could not be afforded in such larger quantities as would be required if they were alloyed with the basic material to a substantial depth. This implantation process thereby enables high cost surfaces to be provided on products at low cost, thereby importantly improving the worth of relatively inexpensive parts.
Ion implantation as a process is widely used in the semi-conductor industry. However, the processing equipment is itself so costly that the process using it is not economically useful generally in industry, except where cost is not a real problem or objection. Surface treatment of helicopter main rotor bearings is an example of an application outside of the semi-conductor industry where the issue of man-safety outweighs any economic objection.
With relatively few exceptions, even medium-cost technology cannot economically enjoy the benefits of ion implantation with the use of existing equipment.
Furthermore, existing techniques are limited in the range and selection of materials which can be made available for ion implantation.
It is an object of this invention to provide elegantly simple devices for ion implantation, whose low capital and operation costs enable them to be used in cost-sensitive applications, and which enable the use of a far wider selection of substances to be implanted than prior art processes and equipment have allowed.